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On Thu, 2004-12-30 at 16:33 -0500, David Megginson wrote:
>
> I find the airplane example interesting, since I just spent the
> morning with my head stuck under an airplane cowling (burned-out
> starter solenoid). Obviously, my Piper is fly-by-loose-cable rather
> than fly-by-wire, but what makes airplane systems safe -- whether
> they're mechanical or electronic -- is not error-free design and
> implementation, but an enormous amount of redundancy.
>
> The trick is to make sure that there are always at least two ways to
> do most things (in a cheap plane like mine; sometimes dozens, in
> commercial airliners) and that they are truly independent of
> each-other.
I don't think that works on EFA and suchlike, particularly not
in the realms of software. Provability and testing rules the day in
that domain. Reliability increases with parallel hardware systems;
Multiple processors similarly help to check each other, but the actual
routines used rely on different approaches.
--
Regards,
Dave Pawson
XSLT + Docbook FAQ
http://www.dpawson.co.uk
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